The present application claims priority under 35 USC 119 to Japanese Patent Application No. 2001-321944 filed on Oct. 19, 2001 the entire contents thereof is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a transmission of a power unit in which an internal combustion engine and the transmission, respectively, for a four-wheel buggy (a saddle-type vehicle for operating on a wasteland) are integrated.
2. Description of Background Art
In a case where three hydraulic clutches are provided to shift between a main shaft and a counter shaft of a transmission, the three clutches are divided into one and two and one clutch and two clutches are arranged on two shafts so as to reduce the axial length of equipment and to simplify hydraulic fluid supply structure. As a center distance is increased when clutches on two shafts are arranged in opposite positions, the center distance is reduced by setting the clutches off in positions that are not opposite. Careful consideration is given to these as problems in the transmission.
In the meantime, heretofore, sufficient consideration is not given to the reduction of the center distance between a crankshaft and a shaft of a transmission, for avoiding interference between a clutch and a torque converter, interference between the clutch and a crank web or interference between the clutch and an alternator.
In the case where a hydraulic clutch is provided on a main shaft of a transmission opposite to a crank web of a crankshaft and an alternator, the center distance between the crankshaft and the main shaft is required to be increased to avoid interference between the equipment. As the outside diameter of a primary driven gear is also increased when the center distance is increased, a crankcase is of a large-sized and the weight is also increased. Particularly, in the case where a crankshaft is arranged longitudinally like a four-wheel buggy (a saddle-type vehicle for operating on a wasteland), the large-size of the crankcase due to an increase of the center distance has a large effect upon the space at the rider""s feet. Thus, riding comfort and operability at the rider""s feet are greatly impaired. It is not desirable in a four-wheel buggy that a hydraulic clutch is provided on a main shaft opposite to a crank web of a crankshaft and an alternator provided on the crankshaft.
The object of the invention is to provide a transmission in which a crankcase is miniaturized and the weight is reduced by providing all three hydraulic clutches at separate locations except the opposite positions without providing a hydraulic clutch on a main shaft opposite to a torque converter, a crank web and an alternator.
The present invention is made to solve the above-identified problems and is based upon a transmission provided with a main shaft and a counter shaft respectively provided in parallel with a crankshaft for transmitting the revolution of a torque converter provided to the crankshaft to the main shaft via a gear. Further the present invention provides for a shifting speed of at three steps by a gear provided on the main shaft and the counter shaft and a hydraulic clutch for connecting or disconnecting the gear. One hydraulic clutch is arranged on the main shaft outside a pair of supports for supporting the main shaft with two gears being fixed apart on the main shaft on both sides close to the support inside the supports for supporting the main shaft and two gears engaged with the two gears fixed to the main shaft and revolvable on the counter shaft. The two gears are arranged in positions on the counter shaft opposite to the insides of the supports of the main shaft and the separate hydraulic clutches for connecting or disconnecting each gear arranged between the two revolvable gears.
As the invention is configured as described above, one clutch provided to the main shaft can be installed in a position not opposite to the crank web and the alternator to avoid interference therewith. As the two clutches are not provided to the main shaft and are installed on the side of the counter shaft, no interference is caused with the torque converter, the crank web and the alternator.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.